Fluid cooling device

ABSTRACT

The invention relates to a fluid cooling device embodied as a modular unit comprising a drive motor ( 10 ) driving a ventilation wheel ( 12 ) and a fluid pump ( 14 ) that supplies a first type of fluid into a fluid system, and leads to a heat exchanger ( 22 ) from which the fluid is redirected into the fluid system in a tempered manner. The inventive device also comprises a extract a second type of fluid from the reservoir ( 30 ) and to supply the same to a second fluid system, from which the second type of liquid is redirected towards the reservoir ( 30 ) in a guiding manner via the first ( 22 ) and the second heat exchanger ( 24 ). Said second fluid operations to be carried out for separate fluid systems, using only one fluid cooling device.

The invention relates to a fluid cooling device as a structural unithaving a drive motor which drives a fan wheel and a fluid pump whichdelivers a first type of fluid to a fluid working circuit which inoperation basically heats the fluid, and leads to a heat exchanger fromwhich the fluid returns cooled to the fluid working circuit.

EP 0 968 371 B1 discloses a fluid cooling device as a structural unitwith a drive motor which drives a fan wheel and a fluid pump which takesfluid (hydraulic medium) from an oil tank and delivers it to a hydraulicworking circuit which heats the fluid, and leads to a heat exchangerfrom which the fluid returns cooled to the oil tank. In the knownsolution the oil tank is made trough-shaped, and with its upwardly drawnedges in the manner of a half shell at least partially encloses themotor and the fluid pump. Accordingly, with the known solution the oiltank has a relatively large volume and is still a component of the fluidcooling device in a space-saving compact design and moreover ensuresgood accessibility of the motor and fluid pump unit for mounting andmaintenance purposes as a result of the installation space left open bythe trough edges. In addition to a compact design for the fluid coolingdevice, the result is moreover that the mass components of the coolingdevice are uniformly distributed, so that in operation a safe uprightposition is achieved even with the corresponding inherent movements andvibrations.

A control system and process for controlling the speed of a plurality offans for cooling a plurality of flow agents in a machine are disclosedin DE 100 62 534 A1, the speed of each fan being controlled according tothe individual heat dissipation requirements of special heat transfercores which are attended by this special fan, this control system havinga plurality of sensors which are positioned to sense the temperature ofeach of the plurality of flow agents, and each sensor can be operated tooutput a signal which indicates the temperature of this special flowagent, and an electronic control device which is coupled to a pluralityof sensors in order to receive signals from them which pick up thetemperature of each of the plurality of flow agents. Based on thesetemperature signals, in the known device the electronic control modulecan determine a corresponding temperature error for each of these flowagents, and based on these temperature error signals and on a certainlogic which has been programmed into the electronic control module, thecontrol device outputs a signal to each of the plurality of fans inorder to individually control their speed, each output signal indicatinga desired fan speed for this special fan.

With the existing solutions however only one cooling task can ever beperformed, i.e., efficient cooling of the heated fluid of a first type,for example in the form of a hydraulic medium. For other cooling andtemperature-control tasks, for example cooling a fluid of a secondhydraulic working circuit (gear oil), the known devices must be providedagain so that an independent cooling device with a drive motor, pump,and cooler consequently is required for each hydraulic circuit and eachcooling task.

On the basis of this prior art, the object of the invention is tofurther improve the known solutions such that severaltemperature-control tasks can be performed with only one fluid coolingdevice. This object is achieved by a fluid cooling device with thefeatures of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, by means ofa second fluid pump of the device a second type of fluid can be takenfrom a storage tank and can be delivered to a second fluid workingcircuit from which the second type of fluid returns in a guided mannerto the storage tank by way of the first and the second heat exchanger,various temperature-control tasks for separate fluid working circuitscan be performed with only one fluid cooling device. Furthermore, withthe solution as claimed in the invention it is possible, especially byway of the first heat exchanger, to effect heat exchange between the twotypes of fluid; this on the one hand leads to a more uniform heat statefor the two fluid media, and on the other can also afford the advantageof heating relatively cold working fluid of a circuit when parts ofmachinery and systems are started by way of the then possible warmerfluid medium of the other circuit in order in this way to clearlyincrease the operating reliability and operating precision.

The fluid cooling device as claimed in the invention is especiallysuited for cooling of electric drives such as linear motors, as are usedfor example in machining centers and machine tools, where cooling of theelectrical components takes place by means of a water-glycol mixture.Furthermore it can be used for other linear motors, motor spindles,servo motors and comparable devices. The cooling medium in the form of awater-glycol mixture as the second type of fluid is relayed to a plateheat exchanger of the fluid cooling device and there in countercurrentcools the hydraulic medium of a hydraulic fluid working circuit to whichlikewise the machining center or the machine tool with its drivablecomponents is connected. Due to the heating caused thereby thewater-glycol mixture, before it travels back into the storage tank ofthe fluid cooling device, is cooled by way of a second heat exchanger inthe form of a finned radiator. During start-up, that is, when thehydraulic working circuit with the connected machining center or machinetool is started up, the hydraulic working medium is generally cold andcan then by heated up by way of the water-glycol medium which has beenheated to a greater degree. A reliable and precise start-up of operationis achieved. Furthermore, in this way the ratio of the temperaturesbetween the electric components and the hydraulic oil of the hydraulicoil circuit can be optimized; this likewise contributes distinctly toimproving the machining precision.

Other advantageous embodiments are the subject matter of the otherdependent claims.

The fluid cooling device as claimed in the invention is detailedschematically below, not to scale, in the drawing of one embodiment.

The single FIGURE shows in a rear view the fluid cooling device as astructural unit in its installation position.

The fluid cooling device shown in its entirety in the FIGURE has anelectric drive motor 10 which drives a fan wheel 12 with individual fanblades. Furthermore, the drive motor 10 drives a fluid pump 14. The fanwheel 12 is held in a fan wheel housing 16 which is built preferablyfrom sheet metal parts. For the sake of safety the fan wheel 12 iscovered with a protective grate 18 in the rear area. In the rear area aflange part 20 which is provided with openings and on which the unitconsisting of the drive motor 10, fan wheel 12 and fluid pump 14 issupported extends over the opening of the fan wheel housing 16. Abovethe fan wheel housing 16 there is a heat exchanger 22 in the form of aplate heat exchanger. Furthermore, toward the front the fan wheelhousing 16 is covered by a second heat exchanger 24 in the form of afinned radiator which extend over the entire free opening cross sectionof the fan wheel opening 26. The fan wheel 12 is designed as an axialintake fan which, viewed in the direction of looking at the FIGURE,draws air from right to left through the fins of the second heatexchanger 24 and moves it rearward into the rear area in the directionof the drive motor 10.

With a suitable adaptation it is however also possible to reverse thisair flow and to design the fluid cooling device as an axial pressurefan. In order to keep the fins of the finned radiator (second heatexchanger) 24 free of dirt, on its free front side it is overlapped by aplate-shaped air filter 28. The fan wheel housing 16 is designed as ahollow box and stands vertically on a storage tank 30 which forms anincreased tank chamber volume to increase its fluid volume in the reararea in the vertical direction. Adjacent to the first drive motor 10 inthe back area of the storage tank 30 a submersible pump 32 is seated onthe latter, the pump parts for removing fluid from the storage tank 30projecting into the latter (not shown). Accordingly the drive motor 34of the submersible pump 32 is visible in the FIGURE. This submersiblepump 32 has a pump opening 36 for removing fluid from the storage tank30.

This pump opening 36 supplies a fluid working circuit which is not shownand which is used preferably for cooling the electric linear drive of amachining center or a machine tool. Especially a water-glycol mixture(second type of fluid) is used as the fluid, and after passing throughthe electrical consumer for its cooling the water-glycol mixture isdelivered by way of the submersible pump 32 into the plate heatexchanger 22, specifically by way of corresponding tubing which is notdetailed and which discharges into the lower port 38 of the plate heatexchanger 22. From there the second type of fluid (water-glycol mixture)flows through the plate heat exchanger 22 and leaves it by way of thelower delivery port 40.

This delivery port 40 is in turn connected to carry fluid to the secondheat exchanger 24 by means of a transverse pipe 42 and the water-glycolmixture which has been heated in the plate heat exchanger 22 is cooledduring operation of the fan wheel 12 by means of cooling air in thesecond heat exchanger 24 in the form of a finned radiator by thewater-glycol mixture traveling in this way through the second heatexchanger 24. After passing through this cooling step, the water-glycolmixture travels by way of the connecting pipe 44 back into the storagetank 30 which in this respect establishes the connection between the topof the storage tank 30 and the top of the second heat exchanger 24 tocarry fluid. After return to the storage tank 30, this water-glycolmixture is available cooled for a new circulation process by means ofthe submersible pump 32.

The already mentioned fluid pump 14 is used to deliver a first type offluid in the form of a hydraulic medium such as hydraulic oil. With thishydraulic oil the hydraulic assemblies of a machining center or amachine tool can appropriately be triggered and operated. The storagetank for the hydraulic oil is located outside of the fluid coolingdevice shown in the FIGURE so that from there the fluid pump 14 intakesthe hydraulic oil by way of its intake opening 46 and relays it to thepump line 48. This fluid-carrying pump line 48 is in turn connected tothe plate heat exchanger 22 above the delivery port 40 by way of theinput opening 50. The hydraulic oil travels by way of the pertinentinput opening 50 into the plate heat exchanger 22 and flows through itin countercurrent to the water-glycol mixture from left to right. Thenthe hydraulic oil which has been cooled or temperature-treated in thisway travels by way of the outlet 52 which is located above the lowerport 38 back into the hydraulic working circuit which is not detailedand to which the hydraulic assembly and the hydraulic tank of the entiresystem are connected.

With the fluid cooling device as claimed in the invention, it istherefore possible to cool heated hydraulic oil of a system by way ofthe plate heat exchanger 22, this cooling or temperature control takingplace in countercurrent by way of the water-glycol mixture which, storedin the storage tank, is delivered by the submersible pump 32 forcirculation. The water-glycol mixture heated in the plate heat exchanger22 is then cooled by way of the finned radiator 24 as it continues tocirculate. If at the start of operation of the hydraulic system thehydraulic medium is cold, it is possible to heat the cold hydraulic oilby way of the water-glycol mixture which may be warmer and in this wayto facilitate the start-up of operation. Furthermore, with respect tothe interface in the form of the first heat exchanger 22 the temperaturebehavior in the two circuits is made uniform; this in turn affects themachining precision for the entire system.

The illustrated fluid cooling device can also be used for otherapplications in which temperature-control tasks for different fluidcircuits arise. Furthermore, it is possible to insert or mount separabletank chambers in the storage tank 30 so that other fluid media can bestored by way of the storage tank of the fluid cooling device as astructural unit. It is also possible, in addition to the illustratedfluid pump 14 and the submersible pump 32, to mount other pumps togetherwith other heat exchangers 22, 24 (not shown) in order to thus triggermore than two fluid media with respect to temperature.

1. Fluid cooling device as a structural unit having a drive motor (10)which drives a fan wheel (12) and a fluid pump (14) which delivers afirst type of fluid to a fluid working circuit and leads to a heatexchanger (22) from which the fluid returns temperature-controlled tothe fluid working circuit, characterized in that by means of a secondfluid pump (32) a second type of fluid can be taken from a storage tank(30) and can be delivered to a second fluid working circuit from whichguided by way of the first (22) and the second heat exchanger (24) thesecond type of fluid returns to the storage tank (30).
 2. The fluidcooling device as claimed in claim 1, wherein the first heat exchanger(22) is a plate heat exchanger which enables exchange of heat betweenthe two types of fluid.
 3. The fluid cooling device as claimed in claim1, wherein the second heat exchanger (24) is a finned radiator whichacquires cooling air from the drivable fan wheel (12) to cool the secondtype of fluid.
 4. The fluid cooling device as claimed in claim 1,wherein the types of fluid consist of a hydraulic medium, the first typeof fluid being a hydraulic oil and the second type of fluid being awater-glycol mixture.
 5. The fluid cooling device as claimed in claim 1,wherein the storage tank (30) is an integral component of the device. 6.The fluid cooling device as claimed in claim 1, wherein the second fluidpump (32) is made as a submersible pump which is seated on the storagetank (30) with its electric drive motor (34).
 7. The fluid coolingdevice as claimed in claim 6, wherein in addition to the first storagetank (30) for the water-glycol mixture there is a second storage tankfor storing the hydraulic oil.
 8. The fluid cooling device as claimed inclaim 1, wherein the drive axes of the two fluid pumps (14, 32) runperpendicular to one another within the device.
 9. The fluid coolingdevice as claimed in claim 1, wherein the connectable first fluidworking circuit has a hydraulic assembly and the connectable secondfluid working circuit has at least one electric drive such as a linearmotor or the like.